The Atomic Theory

1. Two important people in the development of the atomic theory are _____ and _____.

A. Democritus and Avogadro
B. Dalton and Avogadro
C. Democritus and Dalton
D. Bohr and Newton
E. Democritus and Newton

2. Matter is defined as:

A. anything that has temperature and volume
B. anything that has mass and volume
C. anything that that has mass
D. anything that takes up space
E. none of the above

3. The Law of Definite Proportions states that:

A. A chemical compound always contains exactly the same proportion of elements by mass.
B. A chemical compound always contains exactly the same proportion of elements by volume.
C. An element is always the same mass regardless of where it's collected.
D. Mass is always conserved during a chemical reaction.
E. None of the above

4. The Law of Definite Proportions is also called:

A. Dalton's Law
B. Bohr's Law
C. Democritus' Law
D. Proust's Law
E. None of the above

5. The Law of Conservation of Mass states that:

A. Matter can be created but not destroyed in a chemical reaction.
B. Mass cannot be created but can be destroyed in a chemical reaction.
C. Mass is neither created nor destroyed in a chemical reaction.
D. Matter cannot be created but can be destroyed in a chemical reaction.
E. None of the above

Atomic Structure

1. Which of the following is a subatomic particle?

A. Proton
B. Neutron
C. Electron
D. All of the above
E. None of the above

2. Which subatomic particle(s) are found in the nucleus of an atom?

A. Protons and neutrons
B. Protons and electrons
C. Electrons and neutrons
D. Neutrons
E. Electrons

3. Electrons are located _______.

A. in the nucleus of an atom
B. outside of an atom
C. within the orbitals of an atom
D. next to neutrons
E. next to protons

4. The subatomic particle with the smallest mass is the _______.

A. proton
B. neutron
C. electron
D. ion
E. none of the above

5. The uncertainty principle states that:

A. It's impossible to know an electron's exact position and momentum at the same time.
B. It's impossible to know a proton's exact position and momentum at the same time.
C. It's possible to know an electron's exact position and momentum at the same time.
B. It's possible to know a proton's exact position and momentum at the same time.
E. None of the above

Important Atomic Values

1. The mass number is equal to:

A. the number of protons + number of neutrons
B. the atomic number + number of neutrons
C. the mass number + number of neutrons
D. A & B
E. A & C

2. Which of the following is not an isotope of hydrogen?

A. Hydrogen
B. Deuterium
C. Tritium
D. Hydronium

3. What's the atomic symbol of helium?

A. He
B. Hl
C. Hm
D. Hu
E. Hi

4. Isotopes have the same number of:

A. protons
B. electrons
C. neutrons
D. A & B
E. A & C

5. Which of the following statements is incorrect?

A. Isotopes have differing number of neutrons.
B. Isotopes have the same number of electrons.
C. Isotopes have the same mass number.
D. Isotopes have the same number of protons.
E. All of the statements above are correct.

Molecules

1. A molecule is ________.

A. a combination of two or more elements
B. a combination of two or more atoms
C. a combination of exactly two elements
D. a combination of exactly two atoms
E. none of the above

2. Molecules that contain more than two atoms are called:

A. monatomic molecules
B. polyatomic molecules
C. compounds
D. ions
E. none of the above

3. Which of the following is not a diatomic molecule?

A. H₂B. O₂
C. N₂
D. CO
E. All of the above are diatomic molecules

4. A compound is __________.

A. something made up of one and only one element
B. something made up of differently charged species
C. something made up of two or more atoms
D. something made up of two or more elements
E. none of the above

5. Ozone is an example of a(n) ________.

A. polyatomic molecule
B. monatomic molecule
C. ion
D. isotope
E. none of the above

Ions

1. To become an ion, an atom or molecule must:

A. gain or lose an electron
B. gain an electron
C. lose an electron
D. gain or lose a proton
E. none of the above

2. An atom or molecule that gains an electron is called a(n) ______.

A. cation
B. anion
C. negion
D. posion
E. none of the above

3. An atom or molecule that loses an electron is called a(n) ______.

A. cation
B. anion
C. negion
D. posion
E. none of the above

4. When an atom or molecule loses an electron it becomes a(n) ______ and is ______ charged.

A. cation, negatively
B. cation, positively
C. anion, negatively
D. anion, positively
E. none of the above

5. When an atom or molecule gains an electron it becomes a(n) ______ and is ______ charged.

A. cation, negatively
B. cation, positively
C. anion, negatively
D. anion, positively
E. none of the above

Chemical Formulas

1. The molecular formula shows:

A. which elements are present in one mole of a substance
B. how elements are connected in a substance
C. the number of atoms of each element in the smallest unit of a substance in their smallest whole number ratios
D. the exact number of atoms of each element in the smallest unit of a substance
E. none of the above

2. An empirical formula shows:

A. which elements are present in one mole of a substance.
B. how elements are connected in a substance
C. the number of atoms of each element in the smallest unit of a substance in their smallest whole number ratios
D. the exact number of atoms of each element in the smallest unit of a substance
E. none of the above

3. The structural formula shows:

A. which elements are present in one mole of a substance
B. how elements are connected in a substance
C. the number of atoms of each element in the smallest unit of a substance in their smallest whole number ratios
D. the exact number of atoms of each element in the smallest unit of a substance
E. none of the above

4. What is the molecular formula of hydrogen peroxide?

A. H₂O₂
B. HO
C. H-O
D. H₂O₄E. None of the above

5. What is the empirical formula of hydrogen peroxide?

A. H₂O₂
B. HO
C. H-O
D. H₂O₄E. None of the above

Solutions

The Atomic Theory

1. Two important people in the development of the atomic theory are _____ and _____.
C. Democritus and Dalton
Democritus, the Greek Philosopher, and John Dalton, the British schoolteacher, are both considered fathers of the atomic theory.

2. Matter is defined as:
B. anything that has mass and volume
Matter is defined as anything that has mass and takes up space (volume).

3. The Law of Definite Proportions states that:
A. A chemical compound always contains exactly the same proportion of elements by mass.
The Law of Definite Proportions states that a chemical compound always contains exactly the same proportion of elements by mass.

4. The Law of Definite Proportions is also called:
D. Proust's Law
The Law of Definite Proportions is also called Proust's Law because it was developed by Joseph Proust.

5. The Law of Conservation of Mass states that:
C. Mass is neither created nor destroyed in a chemical reaction.
The Law of Conservation of Mass states that mass is neither created nor destroyed in any chemical reaction. Or more simply, the mass of substances produced (products) by a chemical reaction is always equal to the mass of reacting substances (reactants).

Atomic Structure

1. Which of the following is a subatomic particle?
D. All of the above
The three most common subatomic particles that we learned about are protons, neutrons, and electrons.

2. Which subatomic particle(s) are found in the nucleus of an atom?
A. Protons and neutrons
Protons and neutrons are located in the nucleus of an atom, while electrons are located outside the nucleus.

3. Electrons are located _______.
C. within the orbitals of an atom
Protons and neutrons are located in the nucleus of an atom, while electrons are located outside the nucleus in orbitals.

4. The subatomic particle with the smallest mass is the _______.
C. electron
The electron has a negative charge and a negligible mass.

5. The uncertainty principle states that:
A. It's impossible to know an electron's exact position and momentum at the same time.
The uncertainty principle states that it's impossible to know an electron's exact position and momentum at the same time. In other words, if you know the exact location of an electron you have zero information about its or if you know its exact momentum you know nothing about its location.

Important Atomic Values

1. The mass number is equal to:
A. the number of protons + number of neutrons
B. the atomic number + number of neutrons
D. A & B
mass number = number of protons + number of neutrons
= atomic number + number of neutrons

2. Which of the following is not an isotope of hydrogen?
D. Hydronium
Hydrogen, deuterium, and tritium are all isotopes of hydrogen, meaning they have the same number of protons and electrons but a different number of neutrons.

3. What's the atomic symbol of helium?
A. He
The atomic symbol of Helium is He. The atomic symbol is often the first two letters of the element but not always.

4. Isotopes have the same number of:
D. A & BIsotopes of an element have the same number of protons and electrons but differ in the number of neutrons.

5. Which of the following statements is incorrect?
C. Isotopes have the same mass number.
Isotopes have the same number of protons and electrons but differ in the number of neutrons. Because neutrons have mass, isotopes also vary in mass number.

Molecules

1. A molecule is ________.
B. a combination of two or more atoms
A molecule is simply a combination of two or more atoms that can be of the same element or of differing elements.

2. Molecules that contain more than two atoms are called:
B. polyatomic molecules
Molecules that contain more than two atoms are called polyatomic molecules.

3. Which of the following is not a diatomic molecule?
E. All of the above are diatomic molecules
All of the above are diatomic molecules because they contain only two atoms. In diatomic molecules the atoms do not have to be of the same element.

4. A compound is __________.
D. something made up of two or more elements
A compound is something made up of two or more elements, by definition. Not all molecules are compounds.

5. Ozone is an example of a(n) ________.
A. polyatomic molecule
Ozone, O₃, is an example of a polyatomic molecule because it contains more than 2 atoms.

Ions

1. To become an ion, an atom or molecule must:
A. gain or lose an electron
To become an ion a molecule must gain or lose an electron. This will either make it positive or negative.

2. An atom or molecule that gains an electron is called a(n) ______.
B. anion
An atom or molecule that gains an electron is a called an anion. It is negative.

3. An atom or molecule that loses an electron is called a(n) ______.
A. cation
An atom or molecule that loses an electron is called a cation. Losing an electron makes the ion more positive.

4. When an atom or molecule loses an electron it becomes a(n) ______ and is ______ charged.
B. cation, positively
When an atom or molecule loses an electron it becomes a cation and is positively charged.

5. When an atom or molecule gains an electron it becomes a(n) ______ and is ______ charged.
C. anion, negatively
When an atom or molecule gains an electron it becomes anion and is negatively charged.

Chemical Formulas

1. The molecular formula shows:
D. the exact number of atoms of each element in the smallest unit of a substance
The molecular formula shows the exact number of atoms of each element in the smallest unit of a substance.

2. An empirical formula shows:
C. the number of atoms of each element in the smallest unit of a substance in their smallest whole number ratios
The empirical formula shows the number of atoms of each element in the smallest unit of a substance in their smallest whole number ratios.

3. The structural formula shows:
B. how elements are connected in a substance
The structural formula shows how elements are connected in a substance.

4. What is the molecular formula of hydrogen peroxide?
A. H₂O₂
The molecular formula shows the exact number of atoms of each element in the smallest unit of a substance, therefore the molecular formula of hydrogen peroxide is H_2¬O_2.

5. What is the empirical formula of hydrogen peroxide?
B. HO
The empirical formula shows the number of atoms of each element in the smallest unit of a substance in their smallest whole number ratios, therefore the empirical formula of hydrogen peroxide (H₂O₂) is HO.